The rejection states that "iPad" itself is also merely descriptive. If this holds up (and I doubt it will), Microsoft could make a "Microsoft iPad", and LG, Samsung, Asus, would also be able to make "iPad" devices of their own. This would be a disaster for Apple, but I seriously doubt it is going to happen.

"Mini Cooper" isn't merely descriptive -- there's no large Cooper that a Mini Cooper is a small version of.

"M&M's Minis" indeed trademarked, but contains the disclaimer "NO CLAIM IS MADE TO THE EXCLUSIVE RIGHT TO USE "MINIS" APART FROM THE MARK AS SHOWN". The USPTO suggests that if Apple wants the mark, they should re-apply with a similar disclaimer (once they get past iPad itself being descriptive)

"Mac Mini" is not a registered trademark, nor is "iPod Mini"

"iPod Nano" is trademarked without the disclaimer.

"Micro Machines" has a disclaimer on "Machines". It's probably considered other than descriptive because it refers specifically to toy vehicles, not "machines" in a general sense.

There must tons and tons of products and registered trademarks around the name Padmini in India. An actress Padmini (no lastname) [google.com] is the top hit for Padmini in google. I know at least one car model was named Padmini. Every town will have a cafe or a grocery store or a hotel (lodge in local parlance) named Padmini. So I would not be surprised if some one there challenges iPad mini as "too similar to my registered brand name" there. Even if the case has no merit someone might sue just for the publicity or with some hope of reaching a settlement with a multinational company with deep pockets.